阅读说明：本技术 含有四苯基乙烯-三苯胺结构的二胺单体、制备方法及其在制备无色聚酰亚胺中的应用 (Diamine monomer containing tetraphenylethylene-triphenylamine structure, preparation method and application of diamine monomer in preparation of colorless polyimide ) 是由 关绍巍 于铁琛 祝世洋 姚洪岩 田野 王天娇 于 2021-01-05 设计创作，主要内容包括：一种含有四苯基乙烯-三苯胺结构的二胺单体、制备方法及其在制备具有电致变色功能的无色聚酰亚胺中的应用,属于有机化合物制备技术领域。本发明将三苯胺通过醚键与四苯基乙烯相结合,以二胺单体的形式引入聚酰亚胺中；再通过大角度的扭转聚合物主链结构,以及柔性的醚键破坏分子间电荷转移的方式构建聚酰亚胺,不仅在自然状态下达到了完全无色,同时独特四苯基乙烯的中心结构在氧化还原时能发生歧化作用,降低氧化电位,提高电致变色稳定性。实验表明,聚酰亚胺薄膜在自然状态下几乎无可见光吸收,达到无色透明,且随着外加电压的增加,透过率逐渐减弱,变为蓝色,有良好的电致变色性能。(A diamine monomer containing a tetraphenylethylene-triphenylamine structure, a preparation method and application thereof in preparing colorless polyimide with an electrochromic function belong to the technical field of organic compound preparation. Triphenylamine is combined with tetraphenylethylene through ether bonds, and the triphenylamine is introduced into polyimide in the form of diamine monomers; and polyimide is constructed by a mode of breaking intermolecular charge transfer through a large-angle torsion polymer main chain structure and a flexible ether bond, so that complete colorlessness is achieved in a natural state, and simultaneously, the unique tetraphenylethylene central structure can generate disproportionation during oxidation and reduction, the oxidation potential is reduced, and the electrochromic stability is improved. Experiments show that the polyimide film almost has no visible light absorption in a natural state, is colorless and transparent, gradually weakens the transmittance along with the increase of external voltage, turns into blue, and has good electrochromic performance.)

1. A diamine monomer containing a tetraphenylethylene-triphenylamine structure has a structural formula shown as a formula (I):

2. the method for preparing a diamine monomer containing a tetraphenylethylene-triphenylamine structure of claim 1, comprising the steps of:

1) the molar ratio of (1-2): 2-4: 1-2 parts of 4-hydroxydiphenyl ketone, zinc powder and titanium tetrachloride which serve as raw materials, tetrahydrofuran serves as a solvent, and the solid content in a reaction system is 10-20%; adding 4-hydroxydiphenyl ketone and zinc powder into tetrahydrofuran, cooling to-85 to-78 ℃, then dropwise adding titanium tetrachloride, stirring, heating to 80 to 90 ℃ under the protection of nitrogen, reacting for 12 to 24 hours, cooling to room temperature, and then adding 10 wt% of potassium carbonate solution to quench the reaction; filtering the reaction liquid, collecting an organic layer, extracting a filtrate water layer by using ethyl acetate, combining organic phases, drying the organic phases by using magnesium sulfate overnight, evaporating the ethyl acetate and tetrahydrofuran to obtain a solid crude product, recrystallizing the crude product by using methanol, filtering and drying to obtain a white 1, 2-bis (4-hydroxyphenyl) -1, 2-diphenylethylene crystal;

2) the molar ratio of (1-3): 1, p-methoxyaniline and p-fluoronitrobenzene are used as raw materials, and the volume ratio is 20: 1-5% of N, N-Dimethylformamide (DMF) and triethylamine are used as solvents, the solid content in a reaction system is 10-20%, and the reaction is carried out for 60-75 h under the conditions of stirring, nitrogen protection and 80-90 ℃; discharging the reaction liquid into ice water, repeatedly washing the product with deionized water for 4-6 times until the filtrate is colorless and clear, recrystallizing with methanol after vacuum drying, and filtering and drying to obtain orange 4-methoxy-N- (4-nitro) aniline crystals;

3) the molar ratio of (1-2): 2-3: 2-3 parts of 1, 2-bis (4-hydroxyphenyl) -1, 2-stilbene, p-bromofluorobenzene and potassium carbonate are used as raw materials, dimethyl sulfoxide (DMSO) is used as a solvent, the solid content of a reaction system is 10-20%, and the reaction system is heated to reflux under stirring and nitrogen protection and then reacts for 24-48 hours; discharging the reaction liquid into ice water, repeatedly washing and filtering the product for 4-6 times by using deionized water until the filtrate is colorless and clear, and performing vacuum drying on the filtrate by using a volume ratio of 1: performing column chromatography on 1-3 ethyl acetate and petroleum ether to obtain a milky white 1, 2-bis (4- (4-bromophenoxy) benzene) -1, 2-stilbene crystal;

4) the molar ratio of (1-2): 3-4: 3-5: 0.1-0.5: 0.3-0.6 of 4-methoxy-N- (4-nitro) aniline, 1, 2-bis (4- (4-bromophenoxy) benzene) -1, 2-stilbene, potassium tert-butoxide, palladium acetate and tributylphosphine as raw materials, toluene as a solvent, the solid content of a reaction system is 5-20%, and the reaction system is heated to reflux under stirring and nitrogen protection and then reacts for 24-48 h; discharging the reaction liquid into petroleum ether, washing the product for multiple times, drying, recrystallizing with methanol, filtering, and drying to obtain orange 4,4' - ((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (N- (4-methoxyphenyl) -N- (4-nitrophenyl) aniline) crystal;

5) 4,4' - (((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (N- (4-methoxyphenyl) -N- (4-nitrophenyl) aniline) and a palladium-carbon catalyst in a mass ratio of 5-10: 1 is added into 1, 4-dioxane, and the solid content of a reaction system is 5-10%; stirring uniformly under the protection of nitrogen to obtain a suspension, heating to reflux, slowly dropwise adding a hydrazine hydrate solution with the mass fraction of 80 wt% into the suspension, wherein the molar ratio of hydrazine hydrate to 4,4' - ((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (N- (4-methoxyphenyl) -N- (4-nitrophenyl) aniline) is 1-3: 1, continuously refluxing and stirring for 12-48 h; after the reaction is finished, filtering the reaction solution while the reaction solution is hot to remove the palladium-carbon catalyst, discharging the reaction solution into ice water, drying the reaction solution, and mixing the dried reaction solution with the water according to a volume ratio of 1: carrying out column chromatography on 1-3 ethyl acetate and petroleum ether to obtain a product N¹,N¹' - (((((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (4, 1-phenylene)) bis (N)¹- (4-methoxy) benzene-1, 4-diamine), that is, a diamine monomer containing a tetraphenylethylene-triphenylamine structure.

3. Use of the diamine monomer containing tetraphenylethylene-triphenylamine structure according to claim 1 in the preparation of colorless polyimide with electrochromic function.

4. The use of the tetraphenylethylene-triphenylamine structure-containing diamine monomer according to claim 3 in the preparation of colorless polyimide with electrochromic function, wherein: the molar ratio of (1-3): 1, taking a tetraphenylethylene-triphenylamine structure-containing diamine monomer and an anhydride monomer as raw materials, taking N, N-dimethylacetamide as a solvent, reacting at room temperature for 12-24 hours, adding acetic anhydride with the mole number being 30-50 times that of the diamine monomer and pyridine with the mole number being 20-30 times that of the diamine monomer into the system, heating to 100-120 ℃, reacting for 3-5 hours, cooling to room temperature, discharging to ethanol, washing with water and ethanol in a refluxing manner, and drying in vacuum to obtain colorless polyimide.

5. The use of the tetraphenylethylene-triphenylamine structure-containing diamine monomer according to claim 4 for preparing colorless polyimide with electrochromic function, wherein: the acid anhydride is pyromellitic dianhydride, 3',4,4' -benzophenone tetracarboxylic dianhydride, 4,4' -diphenyl ether dianhydride, hexafluoro dianhydride or 1,2,4, 5-cyclohexane tetracarboxylic dianhydride.

6. The use of the tetraphenylethylene-triphenylamine structure-containing diamine monomer according to claim 4 or 5 for preparing colorless polyimide with electrochromic function, wherein: the number average molecular weight Mn of the obtained polyimide is 40000-100000, and the weight average molecular weight is 40000-100000.

Technical Field

The invention belongs to the technical field of organic compound preparation, and particularly relates to a tetraphenylethylene-triphenylamine structure-containing diamine monomer, a preparation method and application thereof in preparation of colorless polyimide with an electrochromic function.

Background

Electrochromism means that the material can change color under the condition of an external electric field and can restore to the original color under the condition of applying a reverse electric field. Under the action of an external electric field, the triphenylamine group is easy to form a stable cation free radical, and charge transfer can occur in the process, so that the color is changed. Due to the twisting structure and large-size conjugation of the tetraphenylethylene structure connected with the olefinic bond, disproportionation is easy to occur during electrochemical reaction, so that structural phase change is initiated, and the oxidation potential is reduced.

Polyimide has been widely studied for a long time due to its excellent electrochemical properties, outstanding mechanical and thermal stability, and especially has great application prospects in the high-tech field. However, the polyimide material generally has a deep color in a natural state due to the intermolecular and intramolecular electron transfer effects thereof, and thus the application of the polyimide material in the field of electrochromism is greatly limited. Meanwhile, the stability of the polyimide material is greatly influenced because the polyimide material generally has higher electrochromic oxidation potential.

Disclosure of Invention

In order to solve the problems, the invention adopts the method that triphenylamine is combined with tetraphenylethylene through ether bond and is introduced into polyimide in the form of diamine monomer. Polyimide is constructed by twisting a polymer main chain structure at a large angle and breaking intermolecular charge transfer through ether bonds, so that complete colorlessness is achieved in a natural state, and simultaneously, a unique tetraphenylethylene central structure can generate disproportionation during oxidation and reduction, so that the oxidation potential is reduced, and the electrochromic stability is improved.

The invention relates to a diamine monomer containing a tetraphenylethylene-triphenylamine structure, which is named as N¹,N¹' - (((((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (4, 1-phenylene)) bis (N)¹- (4-methoxy) benzene-1, 4-diamine) having the formula (I):

the invention relates to a preparation method of a diamine monomer containing a tetraphenylethylene-triphenylamine structure, which comprises the following steps:

1) the molar ratio of (1-2): 2-4: 1-2 parts of 4-hydroxydiphenyl ketone, zinc powder and titanium tetrachloride which serve as raw materials, tetrahydrofuran serves as a solvent, and the solid content in a reaction system is 10-20%; adding 4-hydroxydiphenyl ketone and zinc powder into tetrahydrofuran, cooling to-85 to-78 ℃, then dropwise adding titanium tetrachloride, stirring, heating to 80 to 90 ℃ under the protection of nitrogen, reacting for 12 to 24 hours, cooling to room temperature, and then adding 10 wt% of potassium carbonate solution to quench the reaction; filtering the reaction liquid, collecting an organic layer, extracting a filtrate water layer with ethyl acetate, combining organic phases, drying the organic phases with magnesium sulfate overnight, evaporating the ethyl acetate and tetrahydrofuran to obtain a solid crude product, recrystallizing the crude product with methanol, filtering and drying to obtain a white 1, 2-bis (4-hydroxyphenyl) -1, 2-stilbene crystal, wherein the yield is 50-60%;

the reaction formula is as follows:

2) the molar ratio of (1-3): 1, p-methoxyaniline and p-fluoronitrobenzene are used as raw materials, and the volume ratio is 20: 1-5% of N, N-Dimethylformamide (DMF) and triethylamine are used as solvents, the solid content in a reaction system is 10-20%, and the reaction is carried out for 60-75 h under the conditions of stirring, nitrogen protection and 80-90 ℃; discharging the reaction liquid into ice water, repeatedly washing the product with deionized water for 4-6 times until the filtrate is colorless and clear, recrystallizing with methanol after vacuum drying, and filtering and drying to obtain orange 4-methoxy-N- (4-nitro) aniline crystals with the yield of 50-85%;

the reaction formula is as follows:

3) the molar ratio of (1-2): 2-3: 2-3 parts of 1, 2-bis (4-hydroxyphenyl) -1, 2-stilbene, p-bromofluorobenzene and potassium carbonate are used as raw materials, dimethyl sulfoxide (DMSO) is used as a solvent, the solid content of a reaction system is 10-20%, and the reaction system is heated to reflux under stirring and nitrogen protection and then reacts for 24-48 hours; discharging the reaction liquid into ice water, repeatedly washing and filtering the product for 4-6 times by using deionized water until the filtrate is colorless and clear, and performing vacuum drying on the filtrate by using a volume ratio of 1: performing column chromatography on 1-3 ethyl acetate and petroleum ether to obtain milky white 1, 2-bis (4- (4-bromophenoxy) benzene) -1, 2-stilbene crystals with the yield of 50-85%;

the reaction formula is as follows:

4) the molar ratio of (1-2): 3-4: 3-5: 0.1-0.5: 0.3-0.6 of 4-methoxy-N- (4-nitro) aniline, 1, 2-bis (4- (4-bromophenoxy) benzene) -1, 2-stilbene, potassium tert-butoxide, palladium acetate and tributylphosphine as raw materials, toluene as a solvent, the solid content of a reaction system is 5-20%, and the reaction system is heated to reflux under stirring and nitrogen protection and then reacts for 24-48 h; discharging the reaction liquid into petroleum ether, washing the product for multiple times, drying, recrystallizing with methanol, filtering, and drying to obtain orange 4,4' - ((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (N- (4-methoxyphenyl) -N- (4-nitrophenyl) aniline) crystal with a yield of 50-85%;

the reaction formula is as follows:

5) 4,4' - (((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (N- (4-methoxyphenyl) -N- (4-nitrophenyl) aniline) and a palladium-carbon catalyst (Pd/C) in a mass ratio of 5-10: 1 is added into 1, 4-dioxane, and the solid content of a reaction system is 5-10%; stirring uniformly under the protection of nitrogen to obtain a suspension, heating to reflux, slowly dropwise adding a hydrazine hydrate solution with the mass fraction of 80 wt% into the suspension, wherein the molar ratio of hydrazine hydrate to 4,4' - ((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (N- (4-methoxyphenyl) -N- (4-nitrophenyl) aniline) is 1-3: 1, continuously refluxing and stirring for 12-48 h; after the reaction is finished, filtering the reaction solution while the reaction solution is hot to remove Pd/C, discharging the reaction solution into ice water, drying the reaction solution, and mixing the dried reaction solution with the water according to a volume ratio of 1: carrying out column chromatography on 1-3 ethyl acetate and petroleum ether to obtain a product N¹,N¹' - (((((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (4, 1-phenylene)) bis (N)¹The (4-methoxy) benzene-1, 4-diamine), namely the diamine monomer containing the tetraphenylethylene-triphenylamine structure, proves the structure of the obtained compound through mass spectrum and nuclear magnetic test, and the yield is 70-90%.

The reaction formula is as follows:

the diamine monomer containing the tetraphenylethylene-triphenylamine structure can react with different anhydride monomers to prepare colorless polyimide, and the preparation method comprises the following steps:

the molar ratio of (1-3): 1, taking a tetraphenylethylene-triphenylamine structure-containing diamine monomer and an anhydride monomer as raw materials, taking N, N-dimethylacetamide as a solvent, reacting at room temperature for 12-24 hours, adding acetic anhydride with the mole number of 30-50 times and pyridine with the mole number of 20-30 times of the diamine monomer into the system, heating to 100-120 ℃, reacting for 3-5 hours, cooling to room temperature, discharging to ethanol, washing with water and ethanol in a refluxing manner for several times, and drying in vacuum to obtain colorless polyimide.

The acid anhydride monomer includes, but is not limited to, pyromellitic dianhydride, 3',4,4' -benzophenone tetracarboxylic dianhydride, 4,4' -diphenyl ether dianhydride, hexafluoro dianhydride, and 1,2,4, 5-cyclohexane tetracarboxylic dianhydride.

The polyimide synthesis reaction formula is as follows:

wherein n is an integer between 10 and 80, the number average molecular weight Mn of the obtained polyimide polymer is 40000 to 100000, and the weight average molecular weight is 40000 to 100000;

r isOne kind of (1). The invention has the beneficial effects that:

the twisted tetraphenylethylene structure and the propeller type triphenylamine group are combined together through the flexible ether bond and are introduced into the polyimide in the form of a diamine monomer, and the twisted structure and the large-volume ether bond not only can weaken intermolecular charge transfer, eliminate the color of the polyimide, improve the transmittance and improve the solubility of the polyimide, but also can reduce the oxidation potential of the polyimide and improve the electrochromic stability.

Drawings

FIG. 1: n prepared in example 1¹,N¹' - (((((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (4, 1-phenylene)) bis (N)¹Nuclear magnetic spectrum of- (4-methoxy) benzene-1, 4-diamine).

FIG. 2: n prepared in example 1¹,N¹' - (((((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (4, 1-phenylene)) bis (N)¹(4-methoxy) benzene-1, 4-diamine) mass spectrum.

FIG. 3: infrared image of 1,2,4, 5-Cyclohexanetetracarboxylic dianhydride type polyimide prepared in example 6.

FIG. 4: TGA profile of 1,2,4, 5-cyclohexane tetracarboxylic dianhydride type polyimide prepared in example 6.

FIG. 5: cyclic voltammogram of 1,2,4, 5-cyclohexane tetracarboxylic dianhydride type polyimide prepared in example 6.

FIG. 6: electrochromic spectrum of 1,2,4, 5-cyclohexane tetracarboxylic dianhydride type polyimide prepared in example 6.

FIG. 7: an electrochromic transmittance spectrum of the 1,2,4, 5-cyclohexane tetracarboxylic dianhydride type polyimide prepared in example 6.

FIG. 8: an electrochromic stability spectrum of the 1,2,4, 5-cyclohexane tetracarboxylic dianhydride type polyimide prepared in example 6.

Detailed Description

Example 1: n is a radical of¹,N¹' - (((((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (4, 1-phenylene)) bis (N)¹Preparation of (4-methoxy) benzene-1, 4-diamine

The first step of reaction: 24g of 4-hydroxybenzophenone, 15.7g of zinc powder and 500mL of tetrahydrofuran are added into a 1000mL three-necked flask with mechanical stirring, then cooled to-78 ℃, stirred and added with nitrogen, 23g of titanium tetrachloride is slowly added dropwise, the temperature is returned to room temperature, and then the mixture is heated to 85 ℃ for reaction for 24 hours. After the mixture was cooled again to room temperature, the reaction was quenched with 500mL of a 10 wt% potassium carbonate solution, the organic layer was collected after filtration, the aqueous layer of the filtrate was extracted three times with ethyl acetate, the organic layers were combined and dried over magnesium sulfate overnight, and after ethyl acetate and tetrahydrofuran were distilled off, a solid crude product was obtained which was recrystallized from methanol, filtered and dried to give 12.4g of 1, 2-bis (4-hydroxyphenyl) -1, 2-stilbene as a white crystal with a yield of 51.6%.

The second step of reaction: 36.9g of p-anisidine, 28.2g of p-fluoronitrobenzene, 54mL of triethylamine and 360mL of dry DMF are placed in a 500mL three-necked flask and reacted at 85 ℃ for 72h under mechanical stirring and nitrogen protection. After the reaction is finished, discharging the reaction liquid into ice water under full stirring, repeatedly washing the product for 5 times by using deionized water until the filtrate is colorless and clear, placing the filtrate in a vacuum oven for full drying, recrystallizing the filtrate by using methanol, filtering and drying the filtrate to obtain 30.1g of orange fine needle-shaped crystal 4-methoxy-N- (4-nitro) aniline with the yield of 61 percent.

The third step of reaction: adding 8g of 1, 2-bis (4-hydroxyphenyl) -1, 2-stilbene, 15g of bromobenzene difluoride, 9.6g of potassium carbonate and 80mL of dimethylene into a 500mL three-neck flask, heating the mixture under the protection of nitrogen till reflux reaction for 48 hours, discharging the reaction liquid into ice water, repeatedly washing the product with deionized water for 5 times until the filtrate is colorless and clear, and placing the filtrate in a vacuum oven for full drying. The volume ratio of the dried product is 1: 3, and performing column chromatography on the ethyl acetate and petroleum ether to obtain 10.5g of milky white 1, 2-bis (4- (4-bromophenoxy) benzene) -1, 2-stilbene crystal with the yield of 71 percent.

And a fourth step of reaction: 6g of 1, 2-bis (4- (4-bromophenoxy) benzene) -1, 2-stilbene, 6g of 4-methoxy-N- (4-nitro) aniline, 0.266g of palladium acetate, 0.73g of tri-tert-butylphosphine and 50mL of toluene are added into a 500mL three-necked bottle, the mixture is heated to reflux reaction for 48 hours under the protection of stirring and nitrogen, the reaction liquid is discharged into petroleum ether, the product is washed with water for multiple times and dried, recrystallized by methanol, filtered and dried to obtain 6.3g of orange-yellow crystals of 4,4' - (((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (N- (4-methoxyphenyl) -N- (4-nitrophenyl) aniline) with the yield of 70.7%.

The fifth step of reaction: adding 5g of 4,4' - (((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (N- (4-methoxyphenyl) -N- (4-nitrophenyl) aniline) and 0.7g of palladium carbon catalyst into a 100mL three-necked bottle, heating to reflux by using 50mL of 1, 4-dioxane as a solvent under stirring and nitrogen protection, then slowly dropwise adding 10mL of 80 wt% hydrazine hydrate solution, and continuing to reflux for reaction for 24 hours; after the reaction is finished, filtering the reaction solution while the reaction solution is hot to remove Pd/C, discharging the reaction solution into ice water, drying the reaction solution, and mixing the dried reaction solution with the water according to a volume ratio of 1: 2, and carrying out column chromatography on the ethyl acetate and petroleum ether to obtain light brown crystals N¹,N¹' - (((((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (4, 1-phenylene)) bis (N)¹4.0g of- (4-methoxy) benzene-1, 4-diamine), namely the diamine monomer containing the tetraphenylethylene-triphenylamine structure, the yield is 80.1%.

The nuclear magnetic spectrum shown in fig. 1 shows that the chemical shift attribution of the H atoms is clear and corresponds one to one, which proves the structure of the obtained diamine monomer, and the mass distribution of the mass spectrum shown in fig. 2 also conforms to the diamine monomer. In the present invention, N is¹,N¹' - (((((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (4, 1-phenylene)) bis (N)¹- (4-methoxy) benzene-1, 4-diamine) is a mixture of cis and trans isomers.

Example 2: n is a radical of¹,N¹' - (((((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (4, 1-phenylene)) bis (N)¹- (4-methoxy) benzene-1, 4-diamine) to prepare pyromellitic dianhydride type polyimide.

Into a three-necked flask equipped with a magneton, nitrogen inlet/outlet, and thermometer, 0.329g N obtained in example 1 was charged¹,N¹' - (((((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (4, 1-phenylene)) bis (N)¹- (4-methoxy) benzene-1, 4-diamine) and 0.076g of pyromellitic dianhydride, adding 4mL of N, N-dimethylacetamide (with a solid content of 27%), reacting at room temperature for 24h to obtain viscous polyamic acid, adding 1.4mL of acetic anhydride and 0.7mL of pyridine, heating to 110 ℃ for reacting for 3h, cooling to room temperature after the reaction is finished, discharging to ethanol to obtain a white fibrous product, refluxing and washing with ethanol for 30min, refluxing and washing with water for one time, refluxing and washing with ethanol for 30min, and drying in a vacuum oven at 90 ℃ to obtain 0.33g of pyromellitic dianhydride polyimide with a yield of 82%. The resulting polymer has a number average molecular weight Mn 41785 and a weight average molecular weight Mw 42925 and has the following structural formula:

example 3: n is a radical of¹,N¹' - ((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene) bis (N)¹- (4-methoxyphenyl)) benzene-1, 4-diamine) p-3, 3',4Preparation of polyimide by polymerization of' -benzophenone tetracarboxylic dianhydride

Into a three-necked flask equipped with a magneton, nitrogen inlet/outlet, and thermometer, 0.329g N obtained in example 1 was charged¹,N¹' - (((((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (4, 1-phenylene)) bis (N)¹- (4-methoxy) benzene-1, 4-diamine) and 0.112g of 3,3',4,4' -benzophenone tetracarboxylic dianhydride, 4mL of N, N-dimethylacetamide is added, the mixture reacts for 24 hours at room temperature to obtain viscous polyamic acid, 1.4mL of acetic anhydride and 0.7mL of pyridine are added, the temperature is increased to 110 ℃ for reaction for 3 hours, after the reaction is finished, the mixture is cooled to room temperature, the material is discharged into ethanol to obtain a yellowish white fibrous product, the ethanol is washed in a refluxing mode for 30 minutes, the water is washed in a refluxing mode for one time, the ethanol is washed in a refluxing mode for 30 minutes, and the mixture is dried in a vacuum oven at 90 ℃ to obtain 0.38g of 3,3',4,4' -benzophenone tetracarboxylic dianhydride polyimide, and the yield is 88%. The resulting polymer has a number average molecular weight Mn 49246, a weight average molecular weight Mw 63985, and the formula:

example 4: n is a radical of¹,N¹' - ((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene) bis (N)¹Preparation of polyimide by polymerization of (4-methoxyphenyl)) benzene-1, 4-diamine) p, 4,4' -diphenyl ether dianhydride

Into a three-necked flask equipped with a magneton, nitrogen inlet/outlet, and thermometer, 0.329g N obtained in example 1 was charged¹,N¹' - (((((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (4, 1-phenylene)) bis (N)¹- (4-methoxy) benzene-1, 4-diamine) and 0.108g of 4,4 '-diphenyl ether dianhydride are added, 4mL of N, N-dimethylacetamide is added, the mixture reacts for 24h at room temperature to obtain viscous polyamic acid, 1.4mL of acetic anhydride and 0.7mL of pyridine are added, the temperature is increased to 110 ℃ for reaction for 3h, after the reaction is finished, the mixture is cooled to room temperature, the material is discharged to ethanol to obtain a white fibrous product, ethanol is refluxed and washed for 30min, water is refluxed and washed once, ethanol is refluxed and washed for 30min, and the mixture is dried in a vacuum oven at 90 ℃ to obtain 0.35g of 4,4' -diphenyl ether dianhydride polyimide, wherein the yield is 80%. The obtained polymer has number average molecular weight Mn 52764 and weight average molecular weight Mw 53775, and the structural formula is as follows:

example 5: n is a radical of¹,N¹' - ((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene) bis (N)¹And (4-methoxyphenyl)) benzene-1, 4-diamine) p-hexafluoro dianhydride is polymerized to prepare the polyimide.

Into a three-necked flask equipped with a magneton, nitrogen inlet/outlet, and thermometer, 0.329g N obtained in example 1 was charged¹,N¹' - (((((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (4, 1-phenylene)) bis (N)¹- (4-methoxy) benzene-1, 4-diamine) and 0.155g of hexafluoro dianhydride, adding 4mL of N, N-dimethylacetamide, reacting at room temperature for 24h to obtain viscous polyamic acid, then adding 1.4mL of acetic anhydride and 0.7mL of pyridine, heating to 110 ℃ to react for 3h, cooling to room temperature after the reaction is finished, discharging to ethanol to obtain a yellow fibrous product, refluxing and washing the yellow fibrous product for 30min by using ethanol, refluxing and washing once by using water, refluxing and washing the ethanol for 30min, and drying the yellow fibrous product in a vacuum oven at 90 ℃ to obtain 0.4g of para-hexafluoro dianhydride polyimide with the yield of 82%. The resulting polymer has a number average molecular weight Mn 67562 and a weight average molecular weight Mw 69456, and has the following structural formula:

example 6: n is a radical of¹,N¹' - ((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene) bis (N)¹- (4-methoxyphenyl)) benzene-1, 4-diamine) to 1,2,4, 5-cyclohexane tetracarboxylic dianhydride.

Into a three-necked flask equipped with a magneton, nitrogen inlet/outlet, and thermometer, 0.329g N obtained in example 1 was charged¹,N¹' - (((((1, 2-diphenylethylene-1, 2-) bis (4, 1-phenylene)) bis (oxy)) bis (4, 1-phenylene)) bis (N1- (4-methoxy) benzene-1, 4-diamine) and 0.078g of 1,2,4, 5-cyclohexane tetracarboxylic dianhydride were added to 4mL of N, N-dimethylacetamide, and the mixture was allowed to react at room temperature for 24 hours to obtain a viscous polyamic acid, and then 1.4mL of acetic anhydride was added theretoAnd 0.7mL of pyridine, heating to 110 ℃ for reaction for 3h, after the reaction is finished, cooling to room temperature, discharging to ethanol to obtain a white fibrous product, performing ethanol reflux washing for 30min, performing water reflux washing once, performing ethanol reflux washing for 30min, and drying in a vacuum oven at 90 ℃ to obtain 0.32g of 1,2,4, 5-cyclohexane tetracarboxylic dianhydride polyimide with the yield of 81%. The resulting polymer has a number average molecular weight Mn 78152, a weight average molecular weight Mw 99851, and the formula:

as shown in the IR spectrum of FIG. 3, 1720cm^-1And 1590cm^-1The position is an amido bond characteristic absorption peak, as shown in figure 4, which shows that the 10 percent weight loss temperature is 474 ℃ and the heat resistance stability is very good.

Performance characterization and testing

The electrochromic properties of the prepared polyimide were tested by the following methods: dissolving polyimide polymer in N, N-dimethyl acetamide to prepare solution with the concentration of 50mg/mL, dripping the solution on an ITO glass plate, drying the ITO glass plate to obtain a film with the thickness of 50 mu m, using a platinum wire as a working electrode and Ag/AgNO as a counter electrode₃As a reference electrode, acetonitrile containing 0.1M tetrabutylammonium perchlorate (TBAP) was used as an electrolyte solution. The chemical workstation applies increasing voltages and observes its color change, during which the change in its absorption spectrum is monitored with an ultraviolet-visible spectrometer. Cyclic voltammetry was performed using an electrochemical workstation, as shown in figure 5, demonstrating good redox reversibility. As shown in FIG. 6, when the applied voltage is increased from 0V to 0.6V, the absorption peak at 318nm gradually decreases, new absorption peaks appear at 382nm and 768nm, and the absorption peaks gradually increase with the increase of the applied voltage, and simultaneously, the color of the film changes from colorless to blue. As shown in fig. 7, the film had almost no visible light absorption in its natural state, and was colorless and transparent, and the transmittance gradually decreased with an increase in applied voltage. As shown in FIG. 8, under the detection of 768nm absorption spectrum, 0-0.6V square wave voltage is applied to the sample, and stability detection is carried out on the sample, so that the sample still has good stability after 500 cycles of circulation, and shows that the sample is more stable than the sampleHigh transmission contrast.